Minerals

Encrustations by steam vents in the Stórahver hot spring zone in the Torfajökull Glacier area. The dominant minerals in these encrustations are gypsum, alunogen, halotrichite and pickeringite. With the exception of gypsum, these minerals are highly soluble in water and build up in dry periods only to dissolve in rain. Photograph: Kristján Jónasson.

Minerals are defined as natural, homogenous, solid substances with a specific chemical composition and ordered atomic structure, generally formed through inorganic processes. Over 4000 minerals are known to exist worldwide, of which more than 300 have been found in Iceland.

Minerals may be classified in a number of ways, for example by distinguishing between primary (rock-forming) minerals, i.e., minerals such as olivine and plagioclase (a kind of feldspar) that form as magma cools and rock comes into being, and secondary minerals such as zeolites, which are formed as already existing rocks undergo various processes of change.

Minerals are also classified on the basis of their crystal structure and chemical composition. The IINH makes use of the Nickel-Strunz Classification System (2001), where minerals are divided into 10 main classes on the basis of their composition, which further divided into a number of so-called divisions, subdivisions and groups on the basis of crystal structure and chemical composition. Some groups are organised into families. Certain minerals can be further divided into a number of varieties.Minerals found together in rock, formed under the same conditions and in equilibrium with each other are known as mineral assemblages.

The methodical collection and identification of Icelandic minerals at the IINH began in 1980. Since then, an average of three new Icelandic minerals has been found every year. Research on Icelandic minerals at the IINH has focused mainly on primary minerals in basalt and rhyolite, the formation of secondary minerals in tuff and mineral encrustations associated with a number of eruptions in Iceland. In future, the IINH hopes that its mineral collection will reflect the full diversity of Iceland's mineral wealth.